I don't know about you, but after too much time sitting at my desk or eating too much over the weekend, I find myself scouring the Internet for workout challenges.

It was after Black Friday weekend that I stumbled upon Heather Robertson's 12-week program, which has thousands of views on YouTube. Robertson is a certified personal trainer, nutrition coach, and author who has created a 12-week program that promises to "build strength, burn fat, improve endurance, and boost energy and confidence."

My body hates not moving, so after four days of sitting around writing up fitness information (you're welcome), I felt sluggish and lethargic. I rolled out the mat and chose Day 1 of Robertson's Challenge, a HIIT (High Intensity Interval Training) workout with over 3 million views. The result: My muscles ached as soon as I realized that Robertson's workout targeted muscles I had forgotten about for a while. Read on for more details.

As a fitness editor and enthusiast, I'm always on the lookout for new workouts. From aerial yoga to trampolining, I've tried most of the weird and wonderful fads in the industry. For more inspiration, read about my attempts at Lily Sabri's Squid Game, Brettman Locke's "Absolutely No Ab" Challenge, and Pamela Reif's six-pack ab workout.

Part of the fun of following Robertston's workouts on YouTube is that, unlike other trainers, she does not interrupt the workout to explain the various movements. Like attending a group HIIT class, you just follow along and watch her technique. This full-body workout requires no equipment and can be done anywhere. I used a yoga mat to soften the impact on my joints.

If you'd like to read and follow the workout ahead of time, here's what you can do:

After warming up, do three rounds of the following circuit:

Laydown pushups for 30 seconds: Get down on your stomach, arms and legs in the air, head and torso off the mat. Raise your head and torso off the mat. Arms should be placed next to the body, palms flat on the floor, in a press-up position.

Rest 10 seconds

30 seconds Inchworms: Stand at the edge of the mat, bend at the waist and place both hands flat on the mat. Pause and raise your hands back toward your feet to the starting position. [19] [20] 10-second rest [21] [22] V-squeeze 30 seconds: Lie face down, arms, head, and torso off the mat. At the same time, raise your legs in a V-squeeze, keeping your stomach pressed against the mat. Once in position, pull the arms out to the sides, keeping the elbows bent and the shoulder blades close together. Straighten both arms, return to the original position, and repeat. [23] [24] Rest for 10 seconds [25] [26] Shadow box for 30 seconds: Put one foot in front of the other, focus on your torso, and thrust both arms forward as quickly as possible. The back foot should be on the instep. [27] [28] Rest for 10 seconds [29] [30] Hold elbow plank for 30 seconds: Engage your core and get into a plank position with your weight on your elbows; hold for 30 seconds. [31] [32] Rest 10 seconds [33] [34] Plank jacks for 30 seconds: From the plank position with elbows on the floor, engage your core and be aware that your navel should be sucked into your spine. Jump your legs out to the side as if doing star jumps, then jump back to the original position.

After 30 seconds of rest, perform a second circuit for 3 rounds: [Reverse lunge 30 seconds: Stand with feet under hips, shoulder-width apart, lunge right leg back and lower right knee to a few inches off the ground. Return to starting position and do the same on the left side.

Rest 10 seconds

30 second squat Open feet slightly wider than shoulder width, lower back to squat. Heather holds her arms straight out in front of her, but she may cross her arms or interlace her fingers in front of her body. Pause at the bottom of the squat and then stand up to the starting position.

Rest 10 seconds

Side Lunges 30 seconds Stand with feet shoulder-width apart. Take a large step to the left, bend the left knee and push the hip back. Do the same on the right side.

10-second rest

30-second pop squat In this exercise, start with both feet together and spread them apart until they are shoulder-width apart. Continue to squat down, place your left hand on the floor, and jump back to the starting position. Repeat, this time placing your right hand on the floor. Continue alternating between left and right hands.

Rest 10 seconds

30 seconds chair pose: In chair pose, raise your hands above your head to a low position and hold for 30 seconds. Note that it is tight.

10-second rest

30-second high knees: To raise the knees higher, jog in place and think about raising the knees to your chest each time. Robertson puts his hands above his knees and taps each knee with his hand for range of motion.

I liked the repetitive nature of this workout. By the third round of each circuit, I felt like I had mastered the movement and knew what was coming next. By the third round of each circuit, I felt like I had mastered the moves and knew what was coming next. I also liked the fact that I could do this workout next to my desk between meetings and feel like I had worked hard in a short amount of time. [26] [27] My workouts often focus on one muscle group at a time, so I work my legs on Mondays, arms and abs on Wednesdays, and back and shoulders on Fridays. In between, I try to run or swim or attend yoga or Pilates classes. This full-body workout reminded me how much I have missed going to group classes since the coronavirus outbreak. While I certainly enjoyed working out alone in an empty bedroom, I enjoyed the anxiety of not knowing what was going to happen next and the fast-paced rotation between each exercise.

As strange as it may sound, I also enjoyed Robertston's lack of chatter during the workout; during the 10-second rest period, I could watch a demonstration of the next exercise, but I could also silence my phone or tablet to follow along.

As for how I felt after the workout, my body was sore, but I felt great. I got a killer full-body workout without touching a dumbbell or doing a single burpee, and I can't wait to see what the results of my 12-week workout will be.